The present invention relates to devices for controlling electroerosion working of metals and, in particular, to a device for automatically controlling an electroerosion cutting machine used for working articles with reference to a preselected magnified drawing.
A device is known for automatically controlling an electroerosion cutting machine. It contains a coordinate follow table with a drawing placed thereon, and an optical reading head which moves along the line of the drawing by coordinate drive motors which also move an electroerosion tool relative to the workpiece.
The known device contains a first amplifier whose input is connected to the output of the optical head. The input of a second amplifier is electrically coupled to the erosion gap. The device also includes a unit for selecting the direction of rotation of the drive motors in the course of erosion working. The inputs of this unit are connected to the outputs of a unit for setting the initial conditions of the electroerosion working, as well as to the outputs of the first and second amplifiers. The outputs of the unit for selecting the direction of rotation of the drive motors are electrically connected via a third amplifier and a fourth amplifier to the drive motors which ensure coordinate-wise movement of the optical head and the respective movement of the electroerosion tool.
In this device, the optical head is rotatable. It is provided with an auxiliary drive motor that enables the head to locate a required line in the drawing. As soon as the line is found, the optical head is moved along this line with the aid of the driving motors of the coordinate follow table.
If the line is outside the zone of action of the optical head, the drive motor of the head is again brought into action and turns the head until the line is found.
The direction of further movement of the head along the line in the drawing is determined by the rotation angle of the head. The device operates the drive motors of the coordinate table in reference to this angle.
Preliminary rotation of the head and its subsequent movement in the two coordinates along the line in the drawing account for a low response speed of the device and insufficient accuracy with which the line is followed at steep bends and at high speeds.
Apart from the foregoing considerations, the necessity of a preliminary rotation of the head accounts for its sophisticated design.
The movement of the optical head along the line in the drawing relative to the coordinate table must be synchronized with the movement of the electroerosion tool relative to the workpiece. In the known device, this is attained through a rigid mechanical coupling between the head and the tool via a mechanical reduction gear.
The auxiliary mechanical means for synchronizing the movment of the head and tool do not make it possible to use the known device in combination with a variety of electroerosion cutting machines.
It is rather difficult to use the known device in combination with some of the existing types of machines. It requires additional modifications in the machine's design. It is altogether impossible to use this device with some other types of machines.
In view of the above, it is an object of the present invention to provide a device for automatically controlling an electroerosion cutting machine, having a sufficient operation speed in following lines of a drawing at sharp bends and at high speeds when moving around such bends.
It is another object of the present invention to provide a universal design of an automatic control device which could be used in combination with any type of electroerosion cutting machine.
Another object of the present invention is to provide an automatic control device employing an optical head of a simple design.